There are mainly two types of power supplies, namely analog power supplies and digital power supplies. With the development of power electronics technologies and an increase in application environment complexity, the digital power supplies attract more and more attention because of their excellent features such as strong adaptability, high flexibility, and good extensibility.
A conventional digital power supply generally includes: an analog-to-digital converter (Analog-to-Digital Converter, “ADC” for short), an error amplifier, a digital filter, a digital pulse width modulator (Digital Pulse Width Modulator, “DPWM” for short), a power stage circuit, and a feedback network. The feedback network collects an output signal of the power stage circuit; the error amplifier compares the output signal collected by the feedback network with a reference signal, to obtain an error signal; the ADC converts the error signal from an analog signal into a digital signal, and outputs the digital signal to the digital filter; the digital filter obtains a digital control signal according to the digital signal and sends the digital control signal to the DPWM; and the DPWM generates a pulse width modulation (Pulse Width Modulation, “PWM” for short) signal according to the digital control signal to control an on-off action of a power switch in the power stage circuit, so as to achieve an objective of controlling the output signal of the power stage circuit.
The prior art at least has the following problems:
During running of the digital power supply, especially in the case of start-up or an input surge current shock, the error signal may exceed an input range of the ADC, causing ADC saturation. In this case, if the error signal is greater than a maximum value of the input range of the ADC, the ADC outputs a digital signal corresponding to the maximum value of the input range, causing inaccurate output of the ADC, and further causing instability of an output signal of the digital power supply.